marginal means that adding a mask to distance adds little, likely immaterial, benefit, not absolute zero all the time, as such functional formulations imply. t

marginal means that adding a mask to distance adds little, likely immaterial, benefit, not absolute zero all the time, as such functional formulations imply. transmission is primarily a function of time and distance, which is why imperfect is probabalistically ok. we've already covered distance. passing someone around a corner is a miniscule additional risk because of the time factor. just don't stop to shoot the shit and you'll be fine.